What prop pitch?

[HuskerFanatic]

I am mounting a Mercury 115 2stroke on Crestliner 1750 Fishhawk. With a 90 hp 2 stroke and a 13-1/4 x 17 pitch aluminum prop on this boat the motor turned 5300 rpm which was perfect. The 115 is rated for 4750-5250 rpm. I want to put a stainless 3 blade prop on this motor (I am leaning towards a Ballistic). Should I try a 19 pitch or a 21 pitch? Thanks for any help you can provide.

[rock2me]

I have 1750 FishHawk with a 90hp 2-stroker. I run a 17 pitch aluminum OR a 19 pitch stainless Ballistic - depending on circumstances. My guess is that you will be happy with the 19 on your rig.

Curious, why a new motor? You should try putting a stainless prop on before upgrading to a 115HP? All trimmed up with my 90HP and the stainless prop, I can run low 40's GPS and manage any porpoising. You're only going to see a couple more MPH, 45-47, with a 115HP but you will get a stronger holeshot.

Good Luck

[HuskerFanatic]

I am trading for the 115 because my dealer gave me a good trade price. I simply wanted more horsepower and Mercury`s current warranty and rebate promotions helped make up my mind. I want to prop this 115 for good all around performance as it is used to both fish and pull skiers.

[REW]

Actually, with the 115hp - you are going to see a slight change but not much.
Keep the 17 pitch aluminum for pulling skiiers, and then also get both a 19 and a 21 pitch ballistic.

Depending on the day, and how much load you are carrying, you will find that both of these will work very well.

With a heavier load, the 19 will be best, and for the lighter loads, the 21 will be better.

The load on the engine with the 19 pitch ballistic is almost identical to the load that you put on your current engine with the 17 pitch aluminum.

Also, when you have the 115hp engine mounted, make sure to mount it HIGH. i.e. mount it - starting on the 3rd hole off the transom. This will lift your engine about 2 1/2 - 3 1/2 inches above the transom.
Just by the engine lift, you will likely gain 1-3 mph with the reduced drag of the lower unit.

Again, depending on the hull design, you might find that this height setting is best, or you might have to go up one more hole or drop it a hole.

Bottom line -- continue to lift your engine, until you can't get good prop hookup for the things that you want your boat to do. i.e. if you can't get on plane in the type of water that you run, drop the engine a hole.
On the other hand, if you can pop out of the hole, make decent turns without blow out - then try lifting the motor one more hole. Continue to lift the motor, until you get excessive cavitation, and then drop it down one hole.

At each motor height setting you want to try at least a half dozen props of different sizes and pitches, record all results - hole shots, cavitation issues, speed, etc.

By recording all of the results - for all of the different props, at all of the different motor height settings, you will be able to get exactly the very best performance - for your boat for all of the different load and water conditions that you are likely to encounter.

Take care
REW

[HuskerFanatic]

Thanks for the responses. I appreciate the help. Good fishing!